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MicroRNAs are endogenous non-coding RNAs that play important roles in a wide variety of biological processes such as apoptosis, development, aging and cancer. The aberrant expression of miRNAs may contribute to phenotypic features of malignant cells, including resistance to chemotherapy.
Yang et al BMC Cancer 2014, 14:917 http://www.biomedcentral.com/1471-2407/14/917 RESEARCH ARTICLE Open Access MicroRNA-144 suppresses cholangiocarcinoma cell proliferation and invasion through targeting platelet activating factor acetylhydrolase isoform 1b Rui Yang1,3†, Yongjun Chen1†, Cong Tang2, Hongbo Li1, Bing Wang1, Qun Yan1, Junbo Hu1* and Shengquan Zou1* Abstract Background: MicroRNAs are endogenous non-coding RNAs that play important roles in a wide variety of biological processes such as apoptosis, development, aging and cancer The aberrant expression of miRNAs may contribute to phenotypic features of malignant cells, including resistance to chemotherapy However, in cholangiocarcinoma (CCA) the correlation between miRNAs and their potential roles in CCA remains unclear Methods: MicroRNA profiles were analyzed in three pairs of CCA tumor specimens and non-tumorous-paired biliary tissues using Agilent microRNA microarrays Expression of selected miRNAs was further confirmed in CCA tissues and CCA cell lines by q-PCR The effects of miR-144 were evaluated by cell proliferation, migration, transwell, and tumorigenicity assays Expression of LIS1 (platelet-activating factor acetylhydrolase isoform 1b) was assessed in CCA specimens and CCA cell lines by q-PCR and western blot Targeting of LIS1 by miR-144 was confirmed by luciferase reporter assays Results: We found that the expression of 28 miRNAs in CCA tissues was significantly different from their corresponding adjacent normal bile duct tissues We focused on miR-144 which was significantly down-regulated in CCA tissues Reintroduction of miR-144 in CCA cell lines not only inhibited cell growth, but also significantly reduced cell migration and invasion capacities compared with controls Luciferase assays and western blots verified LIS1 as a direct target of miR-144, and knocking-down LIS1 has similar effect with overexpression of miR-144 in CCA cell lines Moreover, overexpression of miR-144 expression could suppress tumor growth in nude mice Conclusions: Our results showed that miR-144 was reduced in CCA tissues and suggested that miR-144 may be an essential suppresser of CCA cell proliferation and invasion through targeting LIS1 Keywords: CCA, miRNA, Cell proliferation, Cell invasion, LIS1 Background Cholangiocarcinoma (CCA) is a malignant tumor of bile duct epithelial cells, and the incidence and prevalence of CCA have been increasing worldwide over recent decades [1,2] The survival rate of patients with CCA is very poor with a median survival of 6–12 months, as it is most often diagnosed at an advanced stage with intrahepatic and/or * Correspondence: jbhu@tjh.tjmu.edu.cn; sqzou05@aliyun.com † Equal contributors Department of General Surgery, Affiliated Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, China Full list of author information is available at the end of the article lymph node metastases [3-5] Despite advances in surgical techniques, systemic chemotherapy and/or radiotherapy, radical surgery remains the only curative treatment for this devastating disease [6-10] Therefore, an improved understanding of the molecular mechanisms of tumor initiation, progression, and metastasis formation of CCA is urgently required as the basis to identify novel therapeutic targets and develop effective therapeutic strategies MicroRNAs (miRNAs) are endogenous, single-stranded, non-coding, small RNAs that regulate gene expression by preferentially binding to specific sequences in the 3′-untranslated region (3′-UTR) of their target mRNAs [11] © 2014 Yang et al.; licensee BioMed Central Ltd This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated Yang et al BMC Cancer 2014, 14:917 http://www.biomedcentral.com/1471-2407/14/917 Accumulating evidence indicates that aberrant expression of miRNAs contributes to a variety of biological processes including embryonic development and tumorigenesis [12-15] Several studies have demonstrated significant changes of miRNA expression levels in CCA tissue in comparison with paired noncancerous bile duct Furthermore, deregulated miRNAs have been identified that act as oncogenes or tumor suppressors [16-22] These results suggest that miRNAs can contribute to tumor growth, although the possible molecular mechanisms remain to be further elucidated In the present study, we first performed a comprehensive analysis of miRNA expression profiles in CCA tissues and paired noncancerous bile ducts We found that miR144 was significantly down-regulated in CCA tissues and CCA cell lines To investigate the role of miR-144 in cancer cells, we examined the cellular effects of miR-144 overexpression We also identified LIS1 as a novel target gene of miR-144 Furthermore, LIS1 silencing could imitate the phenomenon of miR-144 overexpression These results provide insight into the molecular mechanisms of CCA and may offer a novel therapeutic target in this disease Methods Tissue samples A total of 70 paired human CCA samples with histological evidence were obtained from the Department of Biliary-Pancreatic Surgery, Affiliated Tongji Hospital (Hubei, China) Tumor tissues and the corresponding adjacent normal tissues were frozen in liquid nitrogen and stored at −80°C until use Written informed consent was obtained from all patients and the study was approved by the Institutional Review Boards of the Affiliated Tongji Hospital of Huazhong University of Science and Technology MiRNA microarrays and miRNA target prediction Total RNA was extracted from three CCA tissues and matched adjacent, non-tumor bile duct tissues using TRIZOL (Invitrogen, Carlsbad, CA, USA) according to the supplier’s instructions The miRNA expression profile was determined using the Agilent Human miRNA Microarray Kit (V2) (Agilent Inc., Santa Clara, CA, USA) (Sanger database v.12.0) Hybridized microarray slides were scanned with the Agilent Scanner G2565A and Agilent Feature Extraction version 9.5 was used to extract signals Data analyses including Gene Ontology analysis, Pathway Analysis, and MicroRNA-gene network were performed (shbiochip, Shanghai, China) The target genes of miR-144 were obtained from public databases (miRanda, PicTar, and Target ScanS) according to the following two criteria: the target gene contained the conserved 8-mer and 7-mer sites that match the seed Page of 10 region of miR-144, and the target gene was predicted by at least two programs Cell culture and transient transfection Human embryonic kidney HEK293T cells were obtained from American Type Culture Collection, and human CCA cell lines (HCCC-9810, CCLP1, HuCC-T1, and RBE) were conserved by our laboratory.The nonmalignant cholangiocyte cell line BECwere generously provided by Hiromi Ishibashi, Japan.All cells were maintained in DMEM or RPMI 1640 supplemented with 10% v/v fetal bovine serum (FBS) (Gibco, Grand Island, NY, USA), 100 U/mL penicillin, and 100 μg/mL streptomycin at 37°C in a humidified incubator containing 5% CO2 For transfection, HuCC-T1 and RBE cells were transfected with anti-miR-144 inhibitors (anti-miR144) or Anti-miRNA Inhibitors Negative Control #1 (NC) (Applied Biosystems, Foster City, CA, USA) in a final concentration of 20 nM using X-tremeGENEsiRNA Transfection Reagent (Roche, Indianapolis, IN, USA), according to the manufacturer’s instructions The expression levels of miR-144 were quantified 24 h after transfection, and the cells were examined by western blot analysis 48 h after transfection HCCC-9810 and CCLP1 cells were transfected with specific chemosynthesized siRNA sequences for targeting human LIS1 (gene ID: 5048) or NC The sequences of siRNA are supplied in Additional file 1: Table S1 Silencing of LIS1 was confirmed by western blot analysis 48 h after transfection Plasmid constructs and lentiviral transduction To generate the lentiviral vector pCDH-miR-144 that overexpresses miR-144, a fragment encoding the pre-miR144 sequence was amplified by PCR from HEK293T cell genomic DNA and then cloned into the BamHI/ EcoRI sites of the pCDH-CMV-EF1-copGFP vector (SBI, Mountain View, CA, USA) The sequences of the LIS1 3′-UTR containing putative seed sequences of miR-144 were amplified from CCLP1 genomic DNA and cloned into the psiCHECK™-2 vector (Promega, Madison, WI, USA) The cloned 3′-UTR of LIS1 was mutated using Quickchange (Stratagene, San Diego, CA, USA) The sequences of primer are supplied in Additional file 1: Table S1 The successful sequences and insertions were confirmed by DNA sequencing For production of viral particles, we co-transfected the lentivirus-mediated miR-144 packaging system containing pCDH-CMV-EF1-copGFP or PCDH-miR-144, Rec, TAT, Gag, and Vsvg into HEK293T cells with Lipofectamine™ 2000 (Invitrogen) according to the manufacturer’s instructions The supernatant containing virus source was collected 60 h post-transfection and filtered by a filter with 0.45-μm pore size (Millipore) Yang et al BMC Cancer 2014, 14:917 http://www.biomedcentral.com/1471-2407/14/917 Page of 10 HCCC-9810 and CCLP1 cells were grown in log phase and then transfected with either pCDH-CMV-EF1-copGFP (vector) or PCDH-miR-144 for 12 h Stable cell lines were screened by mass sorting on a FACSAria flow cytometer (BD Biosciences, Mountain View, CA, USA) based on the expression of GFP carried by the lentviral vector 72 h after transfection After 48 h, cells that did not migrate or invade were removed using a cotton swab Invasive cells at the bottom of the membrane were washed twice with PBS, fixed in 4% paraformaldehyde, stained with 0.1% crystal violet, and counted under an inverted microscope All experiments were performed in triplicate and were repeated three times RNA extraction and q-PCR Luciferase reporter assay Total RNA was extracted from CCA cancer tissues or cells using Trizol reagent (Invitrogen) following the manufacturer’s instruction For miR-144 detection, TaqMan miRNA expression assays were used to evaluate the expression of miR-144 using the StepOnePlus™ system (Applied Biosystems) To quantify the LIS1 mRNA levels, 500 ng of total RNA was subjected to first-strand cDNA synthesis using a PrimeScript RT Reagent kit (Takara, Dalian, China) according to the manufacturer’s instructions q-PCR was performed with × SYBR Green PCR master mix (Takara) on the iQ5™ quantitative PCR detection system (Bio-Rad, Richmond, CA, USA) and the results were analyzed with IQ5 software The primers used in the reactions are listed in Additional file 1: Table S1 U6 and GAPDH were used as endogenous controls All reactions were run in triplicate and all experiments were run in triplicate HEK293T cells at 50% confluence in 96-well plates were co-transfected with hsa-miR-144 or anti-miR-144, along with reporter vectors using Lipofectamine™ 2000 The firefly and Renilla luciferase activities were measured 48 h after transfection using the Dual-Luciferase Reporter Assay System (Promega) on an illuminometer (Lumat LB 9507, Berthold, Germany) Renilla luciferase acted as a reporter gene and firefly luciferase as a normalized control for each individual analysis Cell proliferation assays Logarithmic growth phase cells were seeded at a density of × 103 cells per well in a 96-well plate containing 0.1 ml RPMI 1640 medium and 10% FBS Cell Counting Kit-8 (CCK-8) (Dojindo, Tokyo, Japan) reagent was added at 0, 24, 48, and 72 h after seeding and incubated at 37°C for h The data of OD (optical density) value at 450 nm were measured by a microplate reader (Bio-Rad) Each experiment was performed three times with five replicates Cell migration and invasion assays Migration and invasion activities of cells were evaluated by wound healing and invasion assays Cells were seeded in 6-well plates and the confluent monolayer cells (at 80% confluence) were scratched with a sterile 100-μL pipette tip Images of the migrated cells were taken using a digital camera (Leica, Heerburg, Germany) 48 h later The extent of wound healing was assessed by the distance traversed by cells migrating into the denuded area In the invasion assay, the upper chamber of the transwell inserts with 6.5-mm polycarbonate membranes with 8.0-μm pores (Corning) was coated with Matrigel mixed with serum-free medium (diluted at 1:5) (BD Biosciences) A total of × 104 cells were resuspended in serum-free medium and placed in the upper chamber, while 600 μL medium containing 20% FBS was placed in the lower well Tumorigenicity assays in nude mice The use of nude mice complied with the NIH Guide for the Care and Use of Laboratory Animals and local institutional ethical guidelines, and the study was approved by the Experimental Animal Ethics Committee of Tongji Medical College of Huazhong University of Science and Technology Eight mice were used in each group Fourweek-old female nude mice (BALB/c-nude) were injected subcutaneously in the upper back with × 106 CCLP1 cells stably transfected with empty vector or miR-144 vector in 150 μL sterile PBS Tumor growth was measured with calipers every days and the tumor volumes were calculated using the formula: 1/2 (length × width2) Mice were sacrificed and tumor weight was examined weeks later Western blot Cells were harvested with 1× cell lysis buffer (Promega) A total of 60 μg of total proteins were separated on 10% polyacrylamide gel and transferred to nitrocellulose membranes (Bio-Rad) The membranes were blocked with 1% bovine serum albumin in TBST buffer (Tris Buffer Saline containing 0.1% Tween-20) for h at room temperature, and subsequently incubated with antibodies against LIS1 (PA5-20419, pierce), Akt (#4691, Cell Signaling Technology), p-Akt (#4058, Cell Signaling Technology), MMP-2 (#4022, Cell Signaling Technology), or GAPDH (#2118, Cell Signaling Technology) overnight at 4°C After extensive washing with TBST buffer, the blots were then incubated with goat anti-rabbit, horseradish peroxidase-conjugated secondary antibody for h at room temperature Protein bands were detected by enhanced chemiluminescence reagents ECL (Millipore, MA, USA) and the intensity of the bands was analyzed using Image J software (National Institute of Health, USA) Yang et al BMC Cancer 2014, 14:917 http://www.biomedcentral.com/1471-2407/14/917 Statistical analysis Data were expressed as the mean ± standard deviation (SD) Statistical analyses were performed with GraphPad Prism 5.0 (GraphPad Software) miR-144 expression was compared in CCA tissues and matched adjacent, nontumor bile duct tissues by the paired Student’s t test The relationship between miR-144 and LIS1 expression was carried out by Spearman’s correlation A P-value of